DESCRIPTION (Verbatim from Applicant's Abstract): This program combines biomedical engineering research at Riverside Research Institute (RRI) with biological and medical investigations at the Weill Medical College (WMC) of Cornell University. Its first objective is to develop noninvasive, focussed ultrasound procedures for treating malignant ocular tumors, which threaten life, and vitreous hemorrhages and membranes, which threaten sight. Its second objective is to support the safe use of diagnostic ultrasound techniques that promise fundamental advances in detecting and combating ocular disease. Both objectives involve comprehensive scientif aboutc investigations of how ultrasonic energy can modify the diverse tissues of the eye. Therapy investigations involve the development of novel ultrasonic beams to thermally necrose large segments of tumors before blood-flow cooling occurs. These investigations explore adaptively controlled beams whose geometry will allow the rapid treatment of entire tumor volumes while avoiding collateral damage. Novel concepts using crossed beams are being developed to mechanically disrupt vitreous hemorrhages and membranes, and to hasten their resorption before they lead to tractional retinal detachments and blindness. Monitoring procedures, using advanced diagnostic ultrasound concepts, are being investigated to monitor, and ultimately control, tumor and vitreous treatments. All procedures are thoroughly tested in animal-model experiments. Safety studies are investigating pulsed-Doppler and color-flow imaging of the eye, with particular attention to therrnal damage in the absorptive, avascular lens. Very-high-frequency systems, which can resolve fine-scale (50-llm) structures are also being examined. This program has performed the first study of ocular effects at these high frequencies (near 50 MHz). Research will now evaluate potential risks when these frequencies are used with ultrasonic contrast agents to evaluate ciliary-body perfusion in glaucoma assays. Safety will be determined using calibrated exposures in in-vivo animal eyes and comprehensive follow-up examinations. Results will be disseminated to support continued safety as new systems evolve.